Phase 2 Study on the Pharmacokinetics and Safety of RLYB212 in Pregnant Women at Higher Risk for HPA-1a Alloimmunization

Phase 2

Active, not recruiting

• Conditions: Fetal and Neonatal Alloimmune Thrombocytopenia
• Interventions: Drug: Anti-(integrin beta-3) human monoclonal antibody

• Registration Number: NCT06435845
• Lead Sponsor: Rallybio

Brief Summary

The purpose of this Phase 2 study is to assess the pharmacokinetics (PK) and safety of RLYB212 in HPA-1b/b pregnant women at higher risk for HPA-1a alloimmunization and FNAIT.

Detailed Description

This study is a single-arm, open-label, multicenter study of RLYB212 in HPA-1b/b pregnant participants at higher risk for the occurrence of HPA-1a alloimmunization and FNAIT. A laboratory testing paradigm will be applied at screening to identify women at higher risk for HPA-1a alloimmunization. Study IPA2202 is comprised of three phases: a two-part screening phase, an antenatal treatment phase, and a postpartum follow-up phase. Study duration for each participant is anticipated to be \~44 weeks, inclusive of the screening visits through the Week 10 postpartum visit.

Study Timeline

• Study First Submitted: 2024-05-21
• Study First Submitted QC: 2024-05-24
• Study First Posted: 2024-05-30
• Study Start: 2024-11-21
• Status Verified: 2025-04
• Last Update Submitted: 2025-04-10
• Last Update Posted: 2025-04-11
• Primary Completion: 2027-05
• Study Completion: 2027-05

Recruitment & Eligibility

• Status: ACTIVE_NOT_RECRUITING
• Sex: Female
• Target Recruitment: 8

Inclusion Criteria

Pregnant women who present at Gestational Week 6 or after and confirmed to be: HPA-1b/b (HPA-1a negative), HLA-DRB3*01:01 positive, Anti-HPA-1a alloantibody negative, Carrying an HPA-1a/b (HPA-1a positive) fetus

Exclusion Criteria

• Prior history of HPA-1a related fetal and neonatal alloimmune thrombocytopenia
• Multiple pregnancy (more than 1 fetus)
• Prior history of platelet transfusion or other blood transfusions
• Known sensitivity and/or immediate hypersensitivity to any components of RLYB212 or its formulation
• Any co-morbid medical or obstetric condition(s), laboratory abnormality, concomitant treatment, or other reason that, in the investigator's opinion, could adversely affect the safety of the participant and/or fetus, impair the assessment of study results, or preclude compliance with the study

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
RLYB212	Anti-(integrin beta-3) human monoclonal antibody	RLYB212 Subcutaneous injection

Primary Outcome Measures

Name	Time	Method
Number of Participants with treatment related adverse events as defined by CTCAE 5.0	Approx. Gestational Week (GW) <16, 16, 18, 20, 24, 26, 28, 30, 32, 34, 36, 38; at birth (~40), Post Partum (PP) Week 4, 10 week
Maternal exposure to RLYB212 as measured in serum	Approx. GW 16, 18, 20, 24, 26, 28, 30, 32, 34, 36, 38, at birth (~40), PP Week 4

Secondary Outcome Measures

Name	Time	Method
Number of HPA-1a positive neonates with treatment related adverse events as defined by CTCAE v5.0	At birth (~GW 40), Approx. PP Week 4
Pregnancy Outcomes: incidence of live births, spontaneous abortions, elective abortions, still births or premature births	At birth (~GW 40)
Neonatal exposure to RLYB212 as measured in cord blood	At birth (~GW 40)
Anti-RLYB212 antibodies as measured in serum	Approx. GW 16, 20, 24, 28, 32, 36, at birth (~40), PP Week 4
Frequency of Neonatal Thrombocytopenia as measured by platelet count within 72 hours of delivery	At birth (~GW 40)
Frequency of HPA-1a Alloimmunization as measured by anti-HPA-1a alloantibodies	Approx. PP Week 10
Neonatal Outcomes: general health and overall status as defined by absolute values and percentiles	4-6 weeks following delivery

Trial Locations

Locations (3)

Leids Universitair Medisch Centrum; 🇳🇱 Leiden, Zuid-Holland, Netherlands

Oslo University Hospital- Ullevål; 🇳🇴 Oslo, Norway

Södersjukhuset; 🇸🇪 Stockholm, Sweden